title: Regulating amyloid precursor protein synthesis through an internal ribosomal entry site.
abstract: Expression of amyloid precursor protein (APP) is critical to the etiology of Alzheimer's disease (AD). Consequently, regulating APP expression is one approach to block disease progression. To this end, APP can be targeted at the levels of transcription, translation, and protein stability. Little is currently known about the translation of APP mRNA. Here, we report that endogenous APP mRNA is translated in neural cell lines via an internal ribosome entry site (IRES) located in the 5'-untranslated leader. The functional unit of the APP IRES is located within the 5' 50 nucleotides of the 5'-leader. In addition, we found that the APP IRES is positively regulated by two conditions correlated with AD, increased intracellular iron concentration and ischemia. Interestingly, the enhancement of APP IRES activity is dependent upon de novo transcription. Taken together, our data suggest that internal initiation of translation of the APP mRNA is an important mode for synthesis of APP, a mechanism which is regulated by conditions that also contribute to AD.
authors.affiliation: Department of Biochemistry, Neurosciences Program, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA.
authors.forename: Monique E
authors.initials: ME
authors.lastname: Beaudoin
authors.forename: Vincent-Joseph
authors.initials: VJ
authors.lastname: Poirel
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Krushel
mesh_terms: D020121:5' Untranslated Regions; D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis / Q000235:genetics*; D000818:Animals; D002460:Cell Line; D039561:Eukaryotic Initiation Factor-4E / Q000037:antagonists & inhibitors / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D007501:Iron / Q000378:metabolism / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism; D010442:Peptide Chain Initiation, Translational; D011494:Protein Kinases / Q000378:metabolism; D012315:RNA Caps / Q000737:chemistry; D034622:RNA Interference; D051381:Rats; D038621:Regulatory Sequences, Ribonucleic Acid; D019810:Sodium Azide / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D014162:Transfection
chemical_list: D020121:5' Untranslated Regions; D016564:Amyloid beta-Protein Precursor; D039561:Eukaryotic Initiation Factor-4E; D012315:RNA Caps; D038621:Regulatory Sequences, Ribonucleic Acid; D019810:Sodium Azide; D007501:Iron; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases